1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display module having a reduced number of components to minimize a thickness thereof.
2. Description of the Related Art
Generally, there is needed a display device serving as an interface so that a user visually identifies the information processed by an information processing unit. A liquid crystal display shows full colors and has a high resolution. The liquid crystal display is lighter in weight and slimmer than a traditional cathode ray tube. As a result, the liquid crystal display is widely used as a monitor of a typical information processing unit, such as a computer, a domestic wall-mounted television receiver set, or the like.
FIG. 1 is a sectional view illustrating the structure of a conventional liquid crystal display module, and FIG. 2 is a sectional view illustrating a detailed structure of a diffusing plate shown in FIG. 1.
As shown in FIG. 1, a liquid crystal display module 80 includes a display unit 50 having a liquid crystal display panel for displaying an image, and a backlight assembly 60 emitting a light to the display unit 50.
The display unit 50 includes a liquid crystal display panel 59, a data-and-gate printed circuit board (not shown), and a data-and-gate tape carrier package (not shown).
The liquid crystal display panel 59 includes a thin film transistor substrate 52, a color filter substrate 54, and liquid crystal (not shown) interposed between the thin film transistor substrate 52 and the color filter substrate 54.
The thin film transistor substrate 52 includes a transparent glass with a matrix-type thin film transistor formed therein, and the transistor includes a source terminal connected to a data line, a gate terminal connected to a gate line, and a drain terminal having a pixel electrode formed by depositing indium tin oxide (ITO) as a transparent conductive material thereon.
The color filter substrate 54 is provided so as to face the thin film transistor substrate 52, and is formed to have RGB pixels through a thin film forming technique. The RGB pixels are color pixels displaying a desired color when a light passes therethrough. A common electrode of ITO is applied on the entire surface of the color filter substrate 54.
If the thin film transistor 52 is turned on by applying a power to the gate and source terminals of the transistor, an electric field is generated between a pixel electrode and the common electrode of the color filter substrate. An alignment angle of the liquid crystal introduced between the thin film transistor substrate 52 and the color filter substrate 54 is changed by the electric field, and the change of the alignment angle changes the light transmittance, thereby providing a desired pixel.
A backlight assembly 60 is provided under the display unit 50 to uniformly illuminate the display unit 50 from a back surface side of the display unit 50. The backlight assembly includes a lamp unit 10 for generating a light, a light guiding plate 20 for guiding the light toward the display unit 50 and changing a path of the light, an optical sheet 40 for making uniform the brightness of the light illuminated from the light guiding plate 20, and a reflecting plate 30, positioned under the light guiding plate 20, for reflecting the light leaked from the light guiding plate 20 toward the light guiding plate 20 to enhance the light transmission efficiency.
The display unit 50 and the backlight assembly 60 are sequentially inserted into a mold frame (not shown) such as a receptacle, and a top chassis (not shown) is engaged against the mold frame in order to prevent the display unit 50 from being disengaged from the mold frame.
The optical sheet 40 includes a diffusing plate 42 for emitting the light from the light guiding plate 20 as a light having a uniform distribution of brightness, and first and second prism sheets 44 and 46 for controlling the light from the diffusing plate 42 in a different direction to secure a visual angle. In particular, the diffusing plate 42 includes a scattering agent to secure the uniform brightness distribution of light from the light guiding plate 20.
As shown in FIG. 2, the diffusing plate 42 includes a base layer 42a, and first and second diffusing surfaces 42b and 42c covering both surfaces of the base layer 42a. The first and second diffusing surfaces 42b and 42c are provided with a plurality of beads 42d to prevent the light guiding plate 20 from being closely adhered to the diffusing plate 42.
However, in order to improve the wide visual angle and brightness characteristics of the light guiding plate 20, the optical sheet 40 use additional components such as the diffusing plate 42, and the first and second prism sheets 44 and 46. Therefore, the manufacturing cost of the liquid crystal display module increases, and there is a limit in making the LCD module lighter, thinner, and smaller.